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	$216.27	11.443%	$241.0178	$241.02	$241.00	$241.00
Purchase #2	$191.25	3.824%	$198.5634	$198.56	$198.55	$198.60
Purchase #3	$90.46	9.761%	$99.2898	$99.29	$99.30	$99.30
Purchase #4	$52.77	8.674%	$57.3473	$57.35	$57.35	$57.30
Purchase #5	$64.41	13.486%	$73.0963	$73.10	$73.10	$73.10
Purchase #6	$101.34	11.529%	$113.0235	$113.02	$113.00	$113.00
Purchase #7	$228.63	3.581%	$236.8172	$236.82	$236.80	$236.80
7 purchase totals =	$945.13		$1,019.1553	$1,019.16	$1,019.10	$1,019.10