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	$142.32	7.254%	$152.6439	$152.64	$152.65	$152.60
Purchase #2	$209.28	9.687%	$229.553	$229.55	$229.55	$229.60
Purchase #3	$184.88	13.737%	$210.277	$210.28	$210.30	$210.30
Purchase #4	$90.39	3.334%	$93.4036	$93.40	$93.40	$93.40
Purchase #5	$178.90	10.188%	$197.1263	$197.13	$197.15	$197.10
Purchase #6	$169.27	13.176%	$191.573	$191.57	$191.55	$191.60
Purchase #7	$35.98	4.696%	$37.6696	$37.67	$37.65	$37.70
7 purchase totals =	$1,011.02		$1,112.2464	$1,112.24	$1,112.25	$1,112.30