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	$58.73	11.209%	$65.313	$65.31	$65.30	$65.30
Purchase #2	$81.79	8.257%	$88.5434	$88.54	$88.55	$88.50
Purchase #3	$210.84	11.808%	$235.736	$235.74	$235.75	$235.70
Purchase #4	$122.53	13.335%	$138.8694	$138.87	$138.85	$138.90
Purchase #5	$99.83	11.330%	$111.1407	$111.14	$111.15	$111.10
Purchase #6	$230.94	8.322%	$250.1588	$250.16	$250.15	$250.20
Purchase #7	$209.35	6.253%	$222.4407	$222.44	$222.45	$222.40
7 purchase totals =	$1,014.01		$1,112.2020	$1,112.20	$1,112.20	$1,112.10