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	$194.52	8.564%	$211.1787	$211.18	$211.20	$211.20
Purchase #2	$82.91	9.552%	$90.8296	$90.83	$90.85	$90.80
Purchase #3	$196.89	6.491%	$209.6701	$209.67	$209.65	$209.70
Purchase #4	$201.36	8.302%	$218.0769	$218.08	$218.10	$218.10
Purchase #5	$110.35	7.208%	$118.304	$118.30	$118.30	$118.30
Purchase #6	$80.33	11.384%	$89.4748	$89.47	$89.45	$89.50
Purchase #7	$179.97	9.173%	$196.4786	$196.48	$196.50	$196.50
7 purchase totals =	$1,046.33		$1,134.0127	$1,134.01	$1,134.05	$1,134.10