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	$210.40	11.445%	$234.4803	$234.48	$234.50	$234.50
Purchase #2	$53.31	4.470%	$55.693	$55.69	$55.70	$55.70
Purchase #3	$162.27	3.712%	$168.2935	$168.29	$168.30	$168.30
Purchase #4	$190.89	3.690%	$197.9338	$197.93	$197.95	$197.90
Purchase #5	$173.45	3.626%	$179.7393	$179.74	$179.75	$179.70
Purchase #6	$74.80	10.684%	$82.7916	$82.79	$82.80	$82.80
Purchase #7	$93.39	7.546%	$100.4372	$100.44	$100.45	$100.40
7 purchase totals =	$958.51		$1,019.3687	$1,019.36	$1,019.45	$1,019.30