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	$173.45	13.419%	$196.7253	$196.73	$196.75	$196.70
Purchase #2	$24.97	13.701%	$28.3911	$28.39	$28.40	$28.40
Purchase #3	$182.29	4.128%	$189.8149	$189.81	$189.80	$189.80
Purchase #4	$172.28	5.785%	$182.2464	$182.25	$182.25	$182.20
Purchase #5	$196.62	7.270%	$210.9143	$210.91	$210.90	$210.90
Purchase #6	$162.41	7.455%	$174.5177	$174.52	$174.50	$174.50
Purchase #7	$61.26	7.661%	$65.9531	$65.95	$65.95	$66.00
7 purchase totals =	$973.28		$1,048.5628	$1,048.56	$1,048.55	$1,048.50