Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$153.63	4.631%	$160.7446	$160.74	$160.75	$160.70
Purchase #2	$199.88	5.114%	$210.1019	$210.10	$210.10	$210.10
Purchase #3	$169.37	10.334%	$186.8727	$186.87	$186.85	$186.90
Purchase #4	$158.29	5.466%	$166.9421	$166.94	$166.95	$166.90
Purchase #5	$116.38	9.535%	$127.4768	$127.48	$127.50	$127.50
Purchase #6	$110.33	7.541%	$118.65	$118.65	$118.65	$118.70
Purchase #7	$168.83	13.637%	$191.8533	$191.85	$191.85	$191.90
7 purchase totals =	$1,076.71		$1,162.6414	$1,162.63	$1,162.65	$1,162.70