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	$232.88	5.372%	$245.3903	$245.39	$245.40	$245.40
Purchase #2	$6.88	6.671%	$7.339	$7.34	$7.35	$7.30
Purchase #3	$21.82	12.192%	$24.4803	$24.48	$24.50	$24.50
Purchase #4	$204.93	7.125%	$219.5313	$219.53	$219.55	$219.50
Purchase #5	$233.34	9.671%	$255.9063	$255.91	$255.90	$255.90
Purchase #6	$209.73	4.105%	$218.3394	$218.34	$218.35	$218.30
Purchase #7	$82.93	7.760%	$89.3654	$89.37	$89.35	$89.40
7 purchase totals =	$992.51		$1,060.3520	$1,060.36	$1,060.40	$1,060.30