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	$165.37	6.347%	$175.866	$175.87	$175.85	$175.90
Purchase #2	$29.34	13.547%	$33.3147	$33.31	$33.30	$33.30
Purchase #3	$47.90	10.451%	$52.906	$52.91	$52.90	$52.90
Purchase #4	$67.74	4.478%	$70.7734	$70.77	$70.75	$70.80
Purchase #5	$200.59	7.501%	$215.6363	$215.64	$215.65	$215.60
Purchase #6	$115.94	6.338%	$123.2883	$123.29	$123.30	$123.30
Purchase #7	$33.91	5.431%	$35.7517	$35.75	$35.75	$35.80
7 purchase totals =	$660.79		$707.5364	$707.54	$707.50	$707.60