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	$57.93	4.805%	$60.7135	$60.71	$60.70	$60.70
Purchase #2	$161.73	3.443%	$167.2984	$167.30	$167.30	$167.30
Purchase #3	$220.72	3.575%	$228.6107	$228.61	$228.60	$228.60
Purchase #4	$196.31	7.587%	$211.204	$211.20	$211.20	$211.20
Purchase #5	$50.84	5.846%	$53.8121	$53.81	$53.80	$53.80
Purchase #6	$143.34	6.655%	$152.8793	$152.88	$152.90	$152.90
Purchase #7	$149.39	6.365%	$158.8987	$158.90	$158.90	$158.90
7 purchase totals =	$980.26		$1,033.4167	$1,033.41	$1,033.40	$1,033.40