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	$180.81	8.520%	$196.215	$196.22	$196.20	$196.20
Purchase #2	$130.73	8.181%	$141.425	$141.43	$141.45	$141.40
Purchase #3	$200.48	4.408%	$209.3172	$209.32	$209.30	$209.30
Purchase #4	$239.54	5.782%	$253.3902	$253.39	$253.40	$253.40
Purchase #5	$183.76	3.506%	$190.2026	$190.20	$190.20	$190.20
Purchase #6	$168.59	7.288%	$180.8768	$180.88	$180.90	$180.90
Purchase #7	$161.28	5.761%	$170.5713	$170.57	$170.55	$170.60
7 purchase totals =	$1,265.19		$1,341.9981	$1,342.01	$1,342.00	$1,342.00