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	$116.95	7.822%	$126.0978	$126.10	$126.10	$126.10
Purchase #2	$123.43	6.657%	$131.6467	$131.65	$131.65	$131.60
Purchase #3	$229.27	6.556%	$244.3009	$244.30	$244.30	$244.30
Purchase #4	$93.89	10.112%	$103.3842	$103.38	$103.40	$103.40
Purchase #5	$53.91	12.841%	$60.8326	$60.83	$60.85	$60.80
Purchase #6	$163.73	12.600%	$184.36	$184.36	$184.35	$184.40
Purchase #7	$186.93	12.602%	$210.4869	$210.49	$210.50	$210.50
7 purchase totals =	$968.11		$1,061.1091	$1,061.11	$1,061.15	$1,061.10