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	$147.31	10.153%	$162.2664	$162.27	$162.25	$162.30
Purchase #2	$25.92	10.170%	$28.5561	$28.56	$28.55	$28.60
Purchase #3	$64.99	10.621%	$71.8926	$71.89	$71.90	$71.90
Purchase #4	$231.57	13.562%	$262.9755	$262.98	$263.00	$263.00
Purchase #5	$139.62	13.588%	$158.5916	$158.59	$158.60	$158.60
Purchase #6	$110.51	4.563%	$115.5526	$115.55	$115.55	$115.60
Purchase #7	$185.27	13.219%	$209.7608	$209.76	$209.75	$209.80
7 purchase totals =	$905.19		$1,009.5956	$1,009.60	$1,009.60	$1,009.80