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	$213.62	4.444%	$223.1133	$223.11	$223.10	$223.10
Purchase #2	$151.46	11.145%	$168.3402	$168.34	$168.35	$168.30
Purchase #3	$60.39	11.601%	$67.3958	$67.40	$67.40	$67.40
Purchase #4	$107.52	3.427%	$111.2047	$111.20	$111.20	$111.20
Purchase #5	$72.51	6.108%	$76.9389	$76.94	$76.95	$76.90
Purchase #6	$178.35	7.503%	$191.7316	$191.73	$191.75	$191.70
Purchase #7	$248.93	7.874%	$268.5307	$268.53	$268.55	$268.50
7 purchase totals =	$1,032.78		$1,107.2552	$1,107.25	$1,107.30	$1,107.10