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	$222.29	9.432%	$243.2564	$243.26	$243.25	$243.30
Purchase #2	$60.53	12.307%	$67.9794	$67.98	$68.00	$68.00
Purchase #3	$246.79	6.698%	$263.32	$263.32	$263.30	$263.30
Purchase #4	$188.53	11.571%	$210.3448	$210.34	$210.35	$210.30
Purchase #5	$62.61	3.787%	$64.981	$64.98	$65.00	$65.00
Purchase #6	$75.44	4.240%	$78.6387	$78.64	$78.65	$78.60
Purchase #7	$197.57	13.545%	$224.3309	$224.33	$224.35	$224.30
7 purchase totals =	$1,053.76		$1,152.8512	$1,152.85	$1,152.90	$1,152.80